Aerial refueling allows extending the flight ranges of those aircrafts that have been specifically equipped for carrying it out. The in-flight refueling process involves the transfer of fuel from a tanker aircraft to another aircraft to be refueled, the receiver aircraft.
Currently, one of the most used refueling system type is the hose and drogue system. A hose, equipped with a coupling at its end, is deployed from the tanker and the receiver, equipped with a probe, connects in such a coupling. The coupling latches the receiver probe to ensure the connection during the in-flight refuelling operation.
At the end of the hose, the coupling is assembled to a drogue which has different functions, such as to stabilize the hose movements and/or produce enough resistance to ensure the proper connection of the receiver.
Nowadays the assembly between coupling and drogue is performed via several screws which assure the proper joint of the elements.
U.S. Pat. No. 6,375,123 B1 describes a coupling and a drogue, wherein the coupling ends in a flange to which a ring assembly is attached by bolts. The ring assembly comprises an inner ring, an intermediate ring and an outer ring. The struts of the drogue are mounted on the intermediate ring by way of openings, being free to pivot or rotate about the intermediate ring. The intermediate ring with the struts attached is inserted in the inner ring and held therein by fastening outer ring to inner ring. Finally, the whole assembly is attached to the coupling by bolts. In a preferred embodiment, the number of struts is 36. According to this document and in case of repairing or maintaining tasks in the struts or in other part of the coupling and drogue assembly, it is required to remove a large number of pieces which may be not be involved in the malfunctioning, increasing the time required for the repairing, and making the task more difficult.
In a similar way, U.S. Pat. No. 5,921,294 describes a ring assembly that comprises an outer ring and an inner ring, both including an outside diameter and an inside diameter. The inner ring has a plurality of threaded bores located at different degree intervals, and the outer ring, a plurality of counterbores equally positioned. Struts are located between the inner ring and the outer ring, and bolts attach the inner ring to the outer ring clamping the struts therebetween. As described in patent U.S. Pat. No. 6,375,123 B1, these bolts attached the ring assembly to a flange provided at the end of the coupling. Therefore, this invention entails the same limitations as the previously cited document.
Application US 2012/0199696 A1 describes a drogue assembly comprising a coupling and a drogue canopy connected to the coupling by connection means which hold the canopy in an operative, drag producing, position relative to the coupling during refueling. The connection means comprise tether elements (cords and springs), latch elements, and control means for controlling the latch element, wherein the latch element holds the tether element against release to keep the canopy in the operative position. The document focuses on achieving a predictable fly and an easily open up of the drogue when it is ejected into the airstream. The attachments with the coupling are done in a permanently way and trough latch elements which are able to pivot around its mounting between a retaining and a release position of the canopy. Therefore, the drogue assembly described therein results in a complicated embodiment in terms of number of pieces and potential repairing tasks.
Additionally, documents U.S. Pat. No. 6,145,788 and US2010/0019090 A1 describe different drogue assemblies, both based on known ways for the coupling and drogue attachment.
The conventional screw joint between coupling and drogue has several disadvantages for the installation and removal of the coupling and drogue assembly, specifically, it is firstly required to remove their surrounding parts to have access to the joining elements, having to manage several parts even when they are not involved in the damage. In consequence, the operation time needed for the maintenance and repairing tasks increases.
Therefore, it has been detected the need in the aeronautical industry, for a new assembly system for coupling and drogue which is capable of simplifying the installation and removal of the coupling and drogue, avoiding the need of disassembling surrounding pieces, and reducing the time required for maintenance and repairing tasks.